Τμήμα Επιστήμης & Μηχανικής Υλικών
Παρουσίαση Διδακτορικής Διατριβής κ. Χρυσάνθης-Πηνελόπης Αποστολίδου
17 Οκτωβρίου 2023
Επιβλέπουσα Καθηγήτρια: Άννα Μητράκη
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Δευτέρα 23 Οκτωβρίου 2023 και ώρα 12:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής της υποψήφιας διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Χρυσάνθης-Πηνελόπης Αποστολίδου, με θέμα:
«Responsive Self-Assembled Peptide Biomaterials and Applications»
«Αποκρίσιμα Αυτοοργανωμένα Πεπτιδικά Βιοϋλικά και Εφαρμογές»
Περίληψη
“Smart biomaterials" are designed to respond to external stimuli like light, pH, and metals, offering diverse applications from bioimaging to anticancer and antimicrobial applications. Peptides are highlighted as promising components for these materials due to their self-assembly properties, biocompatibility, and bio-functionality. This dissertation investigates peptides in three contexts: first, as a light-responsive delivery system encapsulating porphyrins to create antimicrobial hydrogels, analyzing structure, mechanics, and antimicrobial properties. Second, peptides are used to chelate fluorescent molecules for cancer cell bioimaging, with successful coordination and cell penetration. Finally, biocompatible peptide-metal ion nanoparticles are explored for antibacterial and anticancer purposes, revealing their potential in tumoral environments. The study overall explores smart biomaterial development, focusing on peptides and their responsiveness to external stimuli.”
PhD student position at IESL
11 Οκτωβρίου 2023
In view of the forthcoming start of the HORIZON-EIC-2023-PATHFINDEROPEN-01-01 Project Glas-A-Fuels, entitled “Single-Atom Photocatalysts Enhanced by a Self-Powered Photonic Glass Reactor to Produce Advanced Biofuels”, we are looking to recruit a PhD student for the duration of four years. The experimental work will be implemented in the ULMNP laboratory of IESL-FORTH, while the provisional starting date would be February or March 2024. The main research activities will involve the synthesis, patterning, and characterization of functional composite inorganic oxide glasses.
The applicants are kindly asked to provide their CV to Dr. I. Konidakis (ikonid@iesl.forth.gr) and Dr. E. Stratakis (stratak@iesl.forth.gr).
Requirements:
B.Sc. and M.Sc. in physical sciences (Chemistry, Physics, Materials Science).
Useful links
FORTH: https://www.forth.gr/
IESL-FORTH: http://www.iesl.forth.gr/
ULMNP: http://stratakislab.iesl.forth.gr/ and https://www.iesl.forth.gr/en/research/ULNMP-Group
Παρουσίαση Διδακτορικής Διατριβής κ. Γεωργίου Βαϊλάκη
11 Οκτωβρίου 2023
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του
κ. Γεωργίου Βαϊλάκη
Επιβλέπων Καθηγητής: Γεώργιος Κοπιδάκης
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Πέμπτη 19 Οκτωβρίου 2023 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Γεωργίου Βαϊλάκη , με θέμα:
«Theoretical Study of Two-Dimensional Nanostructures.»
Περίληψη
“Intensive research efforts on two-dimensional (2D) materials of atomic thickness uncover interesting phenomena, exciting physics, and new possibilities for technological innovation. 2D materials show great promise in electronics, optoelectronics, sensing, catalysis, clean energy and environment applications. Following semimetal graphene (Gr), focus is on other stable 2D materials with varying electronic properties such as insulating hexagonal boron nitride (hBN), semiconducting transition metal dichalcogenides (TMDs), and superconducting iron selenide (Fe2Se2). The electronic properties of these materials are strongly affected by strain, nanostructuring, structural and chemical defects, and disorder. Layer by layer stacking of 2D materials gives rise to van der Waals heterostructures (VDWHs) of nanometer thickness and clean interfaces. Superconductivity of twisted bilayer Gr at the magic angle, interlayer excitons in TMD heterostructures and optoelectronic properties of Gr/TMD heterostructures, are examples, among others, where VDWHs significantly differ from their monolayer (ML) constituents. 2D nanostructures often exhibit extraordinary properties and present novel challenges for theory. Theoretical models can answer emerging fundamental questions and identify candidate materials with properties tailored for specific applications from all the range of unique 2D nanostructures. First-principles calculations, which provide solution to the quantum problem and are the basis for atomic-scale understanding of materials, become challenging when deviations from periodicity are strong.
In this work, we perform density functional theory (DFT) calculations for the atomic and electronic structure of defected 2D nanostructures, heterostructures consisting of combinations of TMD MLs, Gr, and other materials. Due to the large size of the simulation cells required, DFT calculations are very demanding and the results need careful interpretation using non-trivial computational tools. We present in detail the methods we develop for the construction of optimized simulation cells and for unfolding the electronic band structures from their Brillouin Zone (BZ). The effective band structure (EBS) produced allows for a clear and direct comparison between electronic properties of 2D defected nanostructures and heterostructures with their pristine or constituent MLs.
Applying our methodology to Gr/TMD and TMD/TMD heterostructures, several experimental observations are explained and predictions are made. Interlayer interactions in Gr/TMD have negligible effects. The Dirac cone of Gr remains unaffected, variations in the TMD electronic band gap are due to the minimal strain remaining in the simulation cells, and Fermi levels move closer to the conduction band minimum. In WX2/MoX2 VDWHs, where X = S, Se, interactions between TMD MLs result in hybridization of electronic states and energy eigenvalues split around the center of the BZ (Γ point). The magnitude of energy splitting depends on the interlayer distance and determines the valence band maximum at the center or the edge (K point) of the BZ. We find that interlayer transitions are more probable in WSe2/MoSe2 than in WS2/MoS2. In all VDWHs we examined, a small but universal redshift of the band gap for the TMDs is observed as opposed to a small blueshift for the Au/MoS2 heterostructure, in agreement with experiments. In hBN/TMD VDWHs, electronic properties of constituent MLs remain unaffected.
Our methodology also proves very useful in investigating defects and adsorption on 2D MLs. In conjunction with experiments, our DFT calculations show how n-doped WSe2 ML becomes a p-doped semiconductor via photochlorination. Energetics and EBSs show that chlorine fills chalcogen vacancies, neutralizing defect states close to the conduction band minimum and creating defect states close to valence band maximum. In another synergy with experiment, our DFT calculations show that Fe-vacancies in Fe2Se2 MLs give rise to a stretched lattice (which remains superconducting) at a relatively low energy cost. The absolute magnetic moment of the Fe atoms near the vacancies increases. Our EBS calculations demonstrate the effects of Fe vacancies in agreement with experiments. Sinking of the hole pocket and creation of new states above the hole pocket and below the electron pocket are produced by Fe vacancies. Finally, we present our theoretical results for hydrogen adsorption on Ni2P/CuCo2S4 heterostructure within another collaboration with experimentalists. Electron transfer towards the CuCo2S4 is related to the superior performance of the heterostructure as a catalyst for hydrogen evolution reaction.
Our DFT-based studies with the methodology we developed for building simulations and interpreting electronic band structures, combined with data from experiments, besides explaining observed phenomena, provide a general framework for making predictions which should be useful in future experiments and applications.”
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του κ. Εμμανουήλ Μανιδάκη
05 Οκτωβρίου 2023
Επιβλέπων Καθηγητής: Νικόλαος Πελεκάνος
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Παρασκευή 13 Οκτωβρίου 2023 και ώρα 12:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Εμμανουήλ Μανιδάκη, με θέμα:«Development of Perovskite-Gallium Arsenide Double-Junction Photovoltaic Devices.»
Περίληψη "The perovskite solar cells represent today the most rapidly developed photovoltaic (PV) technology, as they combine low fabrication costs, high conversion efficiencies and the possibility to deposit on flexible substrates. On the other hand, the GaAs-based solar cells are still regarded as the reference technology in the PV industry, exhibiting the highest PV efficiencies of the field. In this thesis, we combine the benefits of the two material systems to provide a high-efficiency perovskite/GaAs tandem solar cell with enhanced characteristics. Accordingly, we have produced GaAs-based solar cell devices with PV efficiencies reaching ~15% values, comparing well with reported values for GaAs solar cells of similar design. We have developed optimized recipes for the deposition of every single layer of a full perovskite PV device, including the perovskite active layer, the electron and hole transporting layers, and the metal contacts. Specifically, we have successfully synthesized “red” perovskites with a gap around 650 nm needed in tandem perovskite/GaAs structures and have fabricated “red” perovskite solar cells with PV efficiency up to ~6.5%. This relatively modest value is most likely due to the “out-of-the-glovebox” deposition conditions in our laboratory. Nevertheless, combining a 1.77 eV perovskite solar cell provided by a fellow team along with our own GaAs solar cells, we managed to demonstrate a tandem 4-terminal device with a PV efficiency close to 23%, highlighting the benefit of the tandem configuration. Finally, we have shown that the deposition of MAPbI3 on native GaAs substrates is able to generate a giant passivation effect on GaAs, an effect that appears to be fully reversible, in the sense that the perovskite layer can be easily washed away and the PL intensity and spectral features of the GaAs substrate are fully restored to their pristine condition."Παρουσίαση διδακτορικού Γεωργίου Κουρμουλάκη
02 Οκτωβρίου 2023
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής
του κ. Γεωργίου Κουρμουλάκη
Παρασκευή 6 Οκτωβρίου 2023 και ώρα 10:00,
στην αίθουσα Τηλεεκπαίδευσης Ε130
στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης.
Περίληψη
Two-Dimensional Transition Metal Dichalcogenides (2D-TMDs) exhibit remarkable optoelectronic properties, making them pivotal tools in the realization of advanced devices. Their direct bandgap nature, combined with the formation of stable excitons with binding energies on the order of hundreds of meVs, enables robust Photoluminescence (PL) emission even at room temperature. Owing to their atomic thickness and crystal symmetry, these materials are subject to specific optical selection rules in which valley and spin indices are intrinsically coupled creating a binary-like system which can be used for storing and processing information. Despite their resilience to mechanical deformation, 2D-TMDs are extremely sensitive to their dielectric environment.
In this thesis, we investigate how the optical characteristics of a monolayer of WS2 are influenced by the substrate. We achieve this by transferring the two-dimensional materials onto a pre-patterned Si/SiO2 substrate with cylindrical wells resulting in the creation of both suspended and locally strained regions within the same monolayer. We examine this sample configuration with means of optical spectroscopy and non-linear imaging. The distinct PL emission stemming from the neutral exciton (X0) in suspended regions highlights the impact of substrate. Furthermore, we show that Polarization-Resolved Second Harmonic Generation can be an all-optical tool to provide image patterns of the armchair orientation with strain signatures. In the last part of the thesis, we study the impact of biaxial tensile strain on the exciton energy and spin-valley polarization of monolayer WS2 on top of Graphite. Our experimental results allowed us to extract the net effect of biaxial tensile strain to the depolarization, which we have attributed to the decrease of spin relaxation time due to an increase of the effective pseudospin precession frequency combined with the suppressed Κ-Λ scattering channel in the conduction band. Our results demonstrate that substrate modulation and mechanical deformation can be significant tools in tuning the properties of 2D-TMDs in the pursuit of developing novel optoelectronic devices.
Παρουσίαση Διδακτορικής Διατριβής της κ. Δήμητρας Λαδίκα
27 Σεπτεμβρίου 2023
ΠΡΟΣ- Όλα τα μέλη ΔΕΠ του Τμήματος Επιστήμης και Τεχνολογίας Υλικών
- Την Επταμελή Εξεταστική Επιτροπή
- Όλα τα μέλη της Πανεπιστημιακής Κοινότητας
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής της
κ. Δήμητρας Λαδίκα
Επιβλέπουσα: Μαρία Φαρσάρη
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Πέμπτη 5 Οκτωβρίου 2023 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής της υποψήφιας διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Δήμητρας Λαδίκα, με θέμα:"Linear and Nonlinear Optical Properties of Materials for the Development of 3D Photonic Nanostructures at Telecommunication Wavelengths"
Abstract"Nanophotonics possess the ability to manipulate light on the nanoscale which plays a crucial role in the advancement of telecommunication applications. The high-speed transfer of information over long distances has driven to the development of photonic materials and structures in the nanoscale, enabling the manipulation of light, unprecedented speed and precision, surpassing the control of electrons by traditional electronics. In this context, 3D photonic crystals with sub-wavelength resolution emerged as highly promising nanostructures for applications in telecommunications. One promising technique for developing 3D photonic crystals is Multiphoton Lithography (MPL). Multiphoton Lithography (MPL) is a 3D printing technique in the nanoscale based on the multiphoton absorption (MPA) process that offers precise control over the structural attributes including size, resolution and geometry. While many photosensitive materials have demonstrated their suitability for MPL, hybrid photoresists have become increasingly popular over the past decades due to the combination of the unique properties of organic and inorganic components, as well as the potential modification capabilities. However, there remains significant potential to further improve these materials, ultimately enabling increasing the effectiveness of MPL and tailoring the properties of 3D-printed structures for nanophotonic applications. This thesis addresses such advancements, which further involve the utilization of nonlinear optical characterization to optimize 3D nano-structuring in hybrid polymers and novel post-processing approaches to activate the resulted 3D nanostructures in the telecommunication regime."
Πρόγραμμα μαθημάτων χειμερινού εξαμήνου 2023-2024
20 Σεπτεμβρίου 2023
Το πρόγραμμα προπτυχιακών μαθημάτων είναι εδώ.
Το πρόγραμμα μεταπτυχιακών μαθημάτων είναι εδώ.
Έναρξη μαθημάτων τη Δευτέρα 25 Σεπτεμβρίου.
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του κ. Νικολάου Χατζαράκη
19 Σεπτεμβρίου 2023
Επιβλέπων Καθηγητής: Νικόλαος Πελεκάνος
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Δευτέρα 25 Σεπτεμβρίου 2023 και ώρα 11:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Νικόλαου Χατζαράκη, με θέμα:
«Advanced Single-Photon Sources Based on Innovative Semiconductor Nanostructures»
Abstract "Semiconductor quantum dots (QDs) are ideal candidates for producing single photon and entangled photon emitters, which are vital components in quantum information and computing applications. In this thesis, in view of developing practical QD-based single photon emitters, operating at non-cryogenic temperatures with enhanced characteristics, we have focused mainly on self-assembled InAs/GaAs QDs grown on (211)B GaAs substrates. This QD system has all the benefits of standard (100) GaAs QDs, with the additional characteristic of a large piezoelectric field along the growth axis. This piezoelectric field generates large exciton-biexciton splittings, making the system particularly suitable for high temperature single-photon applications. In our case, to achieve high temperature operation, the InAs/GaAs QDs were incorporated in between GaAs/AlAs short-period superlattices. The resulting strong confinement of the carriers inside the dots, drastically improved the temperature stability of the photoluminescence and allowed for single-photon emission at the elevated temperature of 230K, a temperature easily supported by a thermoelectric cooler. Furthermore, the biexciton and trion lines of these strongly-confined InAs QDs were found redshifted with respect to the exciton line, which was attributed to confinement-induced correlation effects, representing an attractive mechanism to tailor the transition energies of a single semiconductor QD by appropriate band-gap engineering of the surrounding barriers. Finally, an alternative way to make high-efficiency nano-emitters is the utilization of the plasmonic effect. Here, the interaction between a semiconductor nanowire emitter and a gold surface is experimentally studied as a function of relative distance. A strong enhancement of the photoluminescence intensity (up to a factor of 40) is observed when the nanowire is lying directly on the metal surface, accompanied by a strong reduction of the carrier recombination lifetime by a factor of 2, that we interpret as due to interaction between the nanowire emitter and surface plasmons."Θέση για διδακτορικό φοιτητή
08 Σεπτεμβρίου 2023
Στα πλαίσια του εγκεκριμένου έργου με τίτλο «Advanced Nanostructured Materials for Sustainable Growth: Green Energy Production/Storage, Energy Saving and Environmental Remediation», Εθνικό Σχέδιο Ανάκαμψης και Ανθεκτικότητας, ζητείται:
ΜΕΤΑΠΤΥΧΙΑΚΟΣ ΦΟΙΤΗΤΗΣ ΓΙΑ ΕΚΠΟΝΗΣΗ ΔΙΔΑΚΤΟΡΙΚΟΥγια να εκπαιδευτεί και να διεξαγάγει έρευνα στην ανάπτυξη και το χαρακτηρισμό νέων νανοδομημένων ημιαγώγιμων υλικών για φωτοκαταλυτικές εφαρμογές και παραγωγή ηλιακών καυσίμων (υδρογόνο).
ΣΤΟ ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΤΕΧΝΟΛΟΓΙΑΣ ΥΛΙΚΩΝ ΤΟΥ ΠΑΝΕΠΙΣΤΗΜΙΟΥ ΚΡΗΤΗΣ
Ο διδακτορικός φοιτητής που θα επιλεγεί, θα λάβει μέσω του προγράμματος οικονομική ενίσχυση που ορίζεται έως 20250 €/έτος και διάρκεια για δύο (2) έτη.
Οι ενδιαφερόμενοι παρακαλούνται να επικοινωνήσουν με τον Καθ. Γεράσιμο Αρματά (Γραφείο Γ.212 – Κτήριο Χημείας, Τηλ. 2810 -545004, email: garmatas@materials.uoc.gr) αποστέλλοντας σύντομο βιογραφικό σημείωμα.
Συμμετοχή των φοιτητών στην αναγόρευση σε επίτιμο διδάκτορα του καθηγητή κ. Krzysztof Matyjaszewski
03 Αυγούστου 2023
ΑΝΑΚΟΙΝΩΣΗ
Σας ενημερώνουμε ότι στις 11.9.2023 στις 11.00 π.μ. στο «ΑΜΦ Πετρίδη» το Τμήμα μας έχει την τιμή να αναγορεύσει σε επίτιμο διδάκτορα τον καθηγητή κ. Krzysztof Matyjaszewski από το Carnegie Mellon University των ΗΠΑ, που είναι ένας από τους πιο διακεκριμένους επιστήμονες στο πεδίο των «Χαλαρών Υλικών». Στα πλαίσια της τελετής αναγόρευσης θα πραγματοποιηθεί ομιλία με τίτλο:«New Materials by Macromolecular Engineering Using ATRP»
H συμμετοχή των φοιτητών μας στην εν λόγω εκδήλωση θα τους δώσει την ευκαιρία να αναβαθμίσουν το γνωστικό τους υπόβαθρο σε θέματα που άπτονται του παραπάνω πεδίου, και για το λόγο αυτό, το Τμήμα θα προχωρήσει σε έκδοση βεβαιώσεων όπως παρακάτω:- Σε όλους τους συμμετέχοντες φοιτητές, βεβαίωση συμμετοχής στη διάλεξη, για να την αναφέρουν στο βιογραφικό τους.
- Για τους φοιτητές που έχουν δηλώσει στο τρέχον ακαδημαϊκό έτος το μάθημα «Εργαστήριο Χαλαρής Ύλης» και συμμετέχουν στην εξεταστική του Σεπτεμβρίου 2022-23, επειδή το θέμα της διάλεξης θεωρείται μέρος της εκπαιδευτικής διαδικασίας του μαθήματος, επιπλέον της παραπάνω βεβαίωσης, θα προσδοθεί και ένας (1) επιπλέον βαθμός, που θα προστεθεί στη τελική βαθμολογία του μαθήματος.
- Για τους φοιτητές όλων των κύκλων σπουδών που πραγματοποιούν «Διπλωματική/Ερευνητική Εργασία» η παρακολούθηση θεωρείται επιβεβλημένη.